Regulation of intestinal apolipoprotein A-I synthesis by dietary phosphatidylcholine in newborn swine

Phospholipid (PL) from both dietary sources and billary secretions may be i mportant in the regulation of intestinal apolipoprotein (apo) synthesis. We previously demonstrated the up-regulation of apo A-l secretion by phosphat idylcholine (PC) in a newborn piglet intestinal epithelial cell line. We hy pothesized that dietary PC increases small intestinal apo A-l synthesis in vivo in the newborn piglet, Two-day-old female swine were fed by gavage for 48 h. Diets consisted of a formula containing 51% of calories as triacylgl ycerol providing 180 kcal/kg/24 h. The experimental group (+PC, n = 7) rece ived 1 g/L added soybean PC, and the control group (-PC, n = 7) received no added PC. At the end of the study period, jejunal apo A-l, B, and A-IV syn thesis was measured, and apo A-l mRNA levels were quantitated. Jejunal muco sal PL content and serum lipids and apo B and A-l levels were measured. Jej unal apo A-l synthesis was almost twice as high in the +PC group as compare d to the -PC group with no difference in apo A-l mRNA levels. Jejunal conte nt of PL was higher in the +PC group than in the -PC group. There were no d ifferences in jejunal apo B and A-IV synthesis or serum levels of lipids an d apo-lipoproteins between-the two groups. Dietary PC supplementation in ne wborn swine up-regulated jejunal apo A-l synthesis. Apo A-IV synthesis, whi ch is sensitive to fatty acid flux, was not significantly increased, which suggests a specific effect of PC on apo A-l synthesis. Lumenal PC may be im portant in the regulation of intestinal apo A-l synthesis in the neonate.